package com.kordar.api.util;

import org.springframework.util.Base64Utils;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * @version V1.0
 * @desc AES 加密工具类
 */
public class AesUtil {

    private static final String KEY_ALGORITHM = "AES";
    private static final String DEFAULT_CIPHER_ALGORITHM = "AES/ECB/PKCS5Padding";//默认的加密算法


    /**
     * AES 加密操作
     *
     * @param content  待加密内容
     * @param password 加密密码
     * @return 返回Base64转码后的加密数据
     */
    public static String encrypt(String content, String password) {
        try {
            Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM);// 创建密码器

            byte[] byteContent = content.getBytes("utf-8");

            cipher.init(Cipher.ENCRYPT_MODE, getSecretKey(password));// 初始化为加密模式的密码器

            byte[] result = cipher.doFinal(byteContent);// 加密

            //Base64是一种基于64个可打印字符来表示二进制数据的表示方法。
            return Base64Utils.encodeToString(result);//通过Base64转码返回
        } catch (Exception ex) {
            Logger.getLogger(AesUtil.class.getName()).log(Level.SEVERE, null, ex);
        }

        return null;
    }

    /**
     * AES 解密操作
     *
     * @param content
     * @param password
     * @return
     */
    public static String decrypt(String content, String password) {

        try {
            Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM);

            cipher.init(Cipher.DECRYPT_MODE, getSecretKey(password));


            byte[] result = cipher.doFinal(Base64Utils.decodeFromString(content));


            return new String(result, "utf-8");
        } catch (Exception ex) {
            Logger.getLogger(AesUtil.class.getName()).log(Level.SEVERE, null, ex);
        }
        return null;
    }

    /**
     * 生成加密秘钥
     *
     * @return
     */
    private static SecretKeySpec getSecretKey(final String password) {
        KeyGenerator kg = null;

        try {

            kg = KeyGenerator.getInstance(KEY_ALGORITHM);
            //AES 要求密钥长度为 128
            SecureRandom secureRandom = SecureRandom.getInstance("SHA1PRNG");
            secureRandom.setSeed(password.getBytes());

            kg.init(128, secureRandom);
//            kg.init(128,secureRandom);
            //生成一个密钥
            SecretKey secretKey = kg.generateKey();
            return new SecretKeySpec(secretKey.getEncoded(), KEY_ALGORITHM);// 转换为AES专用密钥
        } catch (NoSuchAlgorithmException ex) {
            Logger.getLogger(AesUtil.class.getName()).log(Level.SEVERE, null, ex);
        }
        return null;
    }


}